The Cholesterol Myth

Part 1: Introduction

The tragedy of science is the slaying of a beautiful hypothesis by an ugly fact.
T H Huxley

Over the past couple of decades there has been a growing concern about fats and cholesterol. Dieticians, nutritionists and doctors have been telling us that fat is a killer. Governments have introduced national policies based around its reduction. Eat less cholesterol, saturated fat and salt, eat more fibre-rich foods we are all told. The evidence is incontrovertible that if we do not, we are doomed to the West's greatest killer — heart disease.

But is the evidence so clear? Despite the certainty implied by the propaganda, the debate continues in the medical journals, behind the scenes. Is diet a killer? Apart from those with a very rare disease, has cholesterol got anything to do with heart disease — or any other disease? And even if it has, will a change of diet be beneficial?

Like all debates, this one about cholesterol has two sides. The Cholesterol Myth explores the evidence on which present healthy eating' dietary recommendations are based.

Much of the evidence used in the cholesterol debate is complex. Nevertheless, with so much of only one side of the debate having been published and your having been subjected to so much that is misleading, I will try to explain the other side in as much detail as this paper allows.

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THE B. M. A. AND THE GOVERNMENT RECOMMEND THAT THE BRITISH PEOPLE SHOULD DRINK EIGHTY PERCENT MORE MILK, EAT FIFTY-FIVE PERCENT MORE EGGS, FORTY PERCENT MORE BUTTER AND THIRTY PERCENT MORE MEAT.

On the basis of research in the 1920s and 1930s by Sir John Boyd Orr and others, that was the advice given to the British people in 1938. The Government introduced free school milk — full cream, that is — and later we 'went to work on an egg'. As a consequence, child deaths from diphtheria, measles, scarlet fever and whooping cough fell dramatically — well before the introduction of antibiotics and widespread immunisation. Rickets, called 'the English Disease' because it was so wide-spread, and other deficiency diseases were relegated to the past. Other factors helped, but most important of all was the better nutrition that gave children a higher resistance. The recommendations above shaped our diet for nearly fifty years and helped to give us a mean life expectancy that is now among the highest in the world. Sixty years in 1930, our mean life expectancy had climbed to seventy years by 1960 and to seventy-five years by 1990. Now we are told they are shortening our lives — killing us with coronary heart disease. Why the sudden change? To discover that, we need to know something of the history of coronary heart disease and how the strategy to combat it evolved.

Coronary heart disease

There are many diseases that affect the heart but the one that the 'healthy eating' strategies seek to prevent is Coronary Heart Disease (CHD), more correctly called ischaemic heart disease (IHD). CHD is a condition where the coronary arteries that supply blood to nourish the heart muscle are narrowed by a build-up of material on their walls (an atheroma) to such an extent that they become blocked. This cuts off the blood supply to part of the heart muscle, and we have a heart attack. The narrowing also encourages the clotting of blood and, in consequence, it is possible for a clot to cause a heart attack long before the atheroma is large enough to do so. The material generally blamed for the build-up is cholesterol and the 'healthy eating' advice given to the public to reduce the incidence of CHD is aimed simply at reducing the levels of cholesterol in the blood.

Cholesterol

Because of the propaganda, you can be forgiven for thinking that cholesterol is a harmful alien substance that should be avoided at all costs. In fact, nothing could be further from the truth. Cholesterol is an essential component in the body. It is found in all the cells of the body, particularly in the brain and nerve cells. Body cells are continually dying and new ones being made. Cholesterol is a major building block from which cell walls are made. Cholesterol is also used to make a number of other important substances: hormones (including the sex hormones), bile acids and, in conjunction with sunlight on the skin, vitamin D 3 . The body uses large quantities of cholesterol every day and the substance is so important that, with the exception of brain cells, every body cell has the ability to make it.

Cholesterol may be ingested in animal products, but less than twenty percent of your body's cholesterol needs will be supplied in this way. Your body then makes up the difference. If you eat less cholesterol, your body merely compensates by making more. Although the media and food companies still warn against cholesterol in diet, it has been repeatedly demonstrated that the level of cholesterol in your blood is affected very little by the amount of cholesterol you eat.

Cholesterol and CHD

For reasons still unknown, coronary heart disease suddenly took off during the 1920s throughout the industrialised world. By the 1940s it was becoming the major cause of premature death. And nobody knew why.

In 1950 an American doctor, John Gofman, hypothesised that blood cholesterol was to blame. This was supported in 1951 when pathologists were sent to Korea to learn about war wounds by dissecting the bodies of dead soldiers. To their surprise they discovered unexpected evidence of coronary heart disease: unexpected for they knew that death from heart disease was extremely rare under middle age and these men averaged only twenty-two years of age. So the pathologists performed detailed dissections on the hearts of the next 300 corpses. In thirty-five percent they found deposits of fibrous, fatty material sticking to the artery walls. A further forty-one percent had fully formed lesions, and in three percent of the soldiers these lesions were sufficiently large that they blocked at least one coronary artery. Thus, over three-quarters of all the men examined showed evidence of serious coronary heart disease — and they were barely out of their teens.

Doctors now had a problem. As there are no symptoms with the partial blockage of the coronary arteries, how could they tell, without resorting to surgery, who was in danger? They had to find what was different in those with the disease and those free of it.

To cut a long story short, they found cholesterol in the material that builds up on artery walls and causes them to become blocked; people who died of heart disease often had high levels of cholesterol in their blood; and those who suffered the rare hereditary disease, familial hypercholesterolaemia (hereditary high blood cholesterol), also suffered a higher incidence of CHD. And so, not unnaturally perhaps, cholesterol and heart disease became linked.

But there are a number of significant points that the cholesterol theory overlooks. For example, there is a marked difference between the build-up found in those with familial hypercholesterolaemia and those with coronary heart disease: hypercholesterolaemia causes large deposits at the mouths of the coronary arteries, often leaving the arteries themselves unblocked, and so does not reproduce the type of obstruction found in coronary heart disease. People with myxoedema or nephrosis also have high blood cholesterol levels — yet in them, there is no increase in the incidence of CHD. Neither is raised blood cholesterol a predictor of CHD in people over sixty. It has also long been known that simple events, such as putting a cuff around the arm prior to taking a blood sample, or fear of the needle, can result in raised cholesterol values. And, even where these are avoided, large fluctuations are known with peak to nadir variations of as much as twenty-three percent. Lastly, cholesterol is only one of the constituents of an atheroma and, if you think about it, cholesterol is so necessary and so widespread in the body, it would have been surprising if it had not been found. Nevertheless the lowering of blood cholesterol became the sole objective in the fight against CHD; and the two principal methods used to achieve this are with diet and drugs.

References:

J W Gofman, et al. The role of lipids and lipoproteins in atherosclerosis . Science. 1950; 111: 166.
J P Strong, H C McGill jr. The natural history of coronary atherosclerosis. Am J Pathol. 1962; 40: 37.
W F Enos, R H Holmes, J Beyer. Coronary disease among United States soldiers killed in action in Korea. Preliminary report. JAMA 1953; 152: 1090.

Part 2: Fats and Heart Disease

See also www.Cholesterol-and-Health.org.uk, an easy to read website about this whole topic from what cholesterol is, why you need it, and how it is made in the body, to what happens if you take cholesterol-lowering drugs such as statins.

Last updated 18 September 2000

"One must attend in medical practice not primarily to plausible theories but to experience combined with reason." Hippocrates

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